FIG. 1 is a side-sectional view illustrating a conventional discharge valve assembly for a linear compressor, FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1, and FIG. 3 is a perspective view illustrating a discharge valve supporter applied to the conventional discharge valve assembly or the linear compressor.
Referring to FIG. 1, in the conventional discharge valve assembly for the linear compressor, a piston 2 is driven by a linear motor (not shown) and linearly reciprocated inside a cylinder 4, so that a refrigerant sucked into a compression space P formed between the piston 2 and the cylinder 4 can be compressed and discharged into a discharge space D formed at one end of the cylinder 4. A discharge valve 12 is installed to block one end of the cylinder 4. A discharge cap 16 is installed at one end of the cylinder 4 to form the discharge space D, and a ring-shaped discharge valve supporter 18 is stably installed inside the discharge cap 16. A spiral discharge valve spring 14 is installed between the discharge valve 12 and the discharge cap 16, for opening and closing the discharge valve 12 according to a pressure inside the compression space P.
A hole for sucking the refrigerant into the compression space P is formed at the end of the piston 2, and a thin plate type suction valve 6 for opening and closing the hole is screw-fixed to the end of the piston 2. The discharge valve assembly comprising the discharge valve 12, the discharge valve spring 14, the discharge valve supporter 18 and the discharge cap 16 is installed at one end of the cylinder 4, for discharging the refrigerant from the compression space P. The suction valve 6 and the discharge valve assembly are opened and closed according to the pressure inside the compression space P.
Here, one surface 12A of the discharge valve 12 is formed flat to contact closely to one end of the cylinder 4, and the opposite surface 12B thereof is upwardly protruded toward the center, namely, convex. A settling groove 12h is steppedly formed at the center portion of the surface 12B, so that one end of the discharge valve spring 14 can be settled in the settling groove 12h. 
A spiral coil spring is used as the discharge valve spring 14. One end of the discharge valve spring 14 with a small diameter is settled on the discharge valve 12, and the other end of the discharge valve spring 14 with a large diameter is supported by the discharge valve supporter 18.
The discharge cap 16 is formed in a circular cap shape. One end of the discharge cap 16 is fixedly coupled to one end of the cylinder 4. A refrigerant discharge tube (not shown) for externally guiding the refrigerant is connected to one side of the discharge cap 16. As illustrated in FIGS. 2 and 3, the discharge valve supporter 18 is firmed in a ring shape with an L-shaped section, and disposed to surface-contact the inner edge portion of the discharge cap 16.
The discharge valve spring 14 is made of a metal material with high rigidity. Even if the compression space P maintains a high pressure, the discharge valve spring 14 can push the discharge valve 12 toward one end of the cylinder 4. In addition, the discharge cap 16 is made of a metal material with high rigidity. Accordingly, when the high pressure refrigerant compressed in the compression space P is temporarily stored inside the discharge cap 16, the discharge cap 16 can resist the high pressure. In order to prevent the discharge valve spring 14 from directly contacting the discharge cap 16, the discharge valve supporter 18 made of a ductile material is installed inside the discharge cap 16.
The process of discharging the refrigerant will now be explained. When the piston 2 is linearly reciprocated inside the cylinder 4, if the pressure inside the compression space P is below a set discharge pressure, the discharge valve 12 contacts closely to one end of the cylinder 4 by an elastic force of the discharge valve spring 14, thereby preventing discharge of the refrigerant. Conversely, if the pressure inside the compression space P is over the set discharge pressure, the discharge valve spring 14 is compressed to make the discharge valve 12 open one end of the cylinder 14, thereby discharging the compressed refrigerant.
In the conventional discharge valve assembly for the linear compressor, the discharge valve 12 is installed at one end of the cylinder 4 and opened and closed by the discharge valve spring 14. One end of the discharge valve spring 14 is supported by the discharge valve 12, and the other end thereof is supported by the discharge cap 16 fixed to one end of the cylinder 4 and the discharge valve supporter 18 settled in the discharge cap 16. As a result, vibration generated by linear reciprocation of the piston 2 inside the cylinder 4 is transferred to the discharge valve supporter 18 and the discharge cap 16 surface-contacting the discharge valve supporter 18 through the discharge valve spring 14, and amplified to increase noise.